Khairul Anuar Kassim

Stabilization of tropical kaolin soil with phosphoric acid and lime

Studies on the chemically stabilized soils have shown that the effectiveness of treatment is largely dependent on soil’s natural environment. In tropical kaolin soils, phosphoric acid may be used as an alternative to traditional alkaline stabilizers for improving soil properties. This research was carried out in an effort to identify the time-dependent soil-stabilizer reactions. Data for the study of characterization of treated samples were obtained from X-ray diffractometry, energy dispersive X-ray spectrometry, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and leaching analysis. Based on the collected data, the kaolinite mineral with pH-dependent structural properties showed slightly different behavior both in basic and in acidic mediums. Also, it was found that the chemical stabilizers preferentially attacked the alumina surface of the clay particles. Therefore, it was rational to suggest that with respect to lime and phosphoric acid treatment, aluminate hydrate compounds are more likely to be formed.

Simulation comparison of the dispersion behaviour of dry sand subjected to explosion

This research simulated the dispersion behavior of sand subjected to explosion on the surface of a sand layer. The simulation was conducted using AUTODYN. Explosion effects from an explosive were achieved by using the computer program, Conventional Weapon Effects Backfill (CONWEB), which was based on field data compiled by the U.S. Army (US Army, 1986). Three different governing equations were used for air, sand and explosive. Ideal gas equation was used to equate the movement of air and the dry sand was based on the compaction effort. For the explosion, the JWL (Jones-Wilkins-Lee) equation was used. This paper presents the effect of explosion on the crater depth, crater diameter and overpressure exerted on sand and the surrounding air. The results have shown that crater depth and diameter increase with time during explosion. The experimental data on crater depth, however, were initially lower than the numerical simulation, but after 30 ms, it increased more than the numerical simulation. The overpressure showed a reducing trend with time. The numerical simulation, based on AUTODYN, predicted higher crater depth and overpressure at the initial stage, but showed a good agreement with the experimental data with time.

Size Distribution Analysis of Kaolin Using Laser Diffraction Technique

Kaolin is widely used in ceramic, paper, and pharmaceutical industries. The suitability use of kaolin in industries will depend on its physical and chemical properties. The physical and chemical composition of Kaolin is dependent on its geological origin, geographic source and processing. Processed kaolin available in the market is normally graded by the manufacturer based on its physical and chemical composition. This paper is focused on the size distribution analysis of nine types/batches of processed kaolin and one raw kaolin soil by using laser diffraction technique (based on Fraunhofer diffraction theory) in accordance to BS ISO 13320:2009. The laser diffraction technique is widely used in the powder industries in determining the particle size distribution because of its simplicity and its repeatability. All the specimens were pre-sieved with a sieve of 2mm aperture size. The effective size, uniformity coefficient and coefficient of curvature of the material were also calculated to facilitate the size distribution analysis. The findings of this paper are expected to benefit industries in which size the distribution of the kaolin will directly or indirectly contribute to its suitability use.

Development of p-y curves of laterally loaded piles in cohesionless soil.

The research on damages of structures that are supported by deep foundations has been quite intensive in the past decade. Kinematic interaction in soil-pile interaction is evaluated based on the p-y curve approach. Existing p-y curves have considered the effects of relative density on soil-pile interaction in sandy soil. The roughness influence of the surface wall pile on p-y curves has not been emphasized sufficiently. The presented study was performed to develop a series of p-y curves for single piles through comprehensive experimental investigations. Modification factors were studied, namely, the effects of relative density and roughness of the wall surface of pile. The model tests were subjected to lateral load in Johor Bahru sand. The new p-y curves were evaluated based on the experimental data and were compared to the existing p-y curves. The soil-pile reaction for various relative density (from 30% to 75%) was increased in the range of 40–95% for a smooth pile at a small displacement and 90% at a large displacement. For rough pile, the ratio of dense to loose relative density soil-pile reaction was from 2.0 to 3.0 at a small to large displacement. Direct comparison of the developed p-y curve shows significant differences in the magnitude and shapes with the existing load-transfer curves. Good comparison with the experimental and design studies demonstrates the multidisciplinary applications of the present method.

Behaviour of expanded piles under upward loading due to radial preloading in soft clay

A two-dimensional numerical analysis was employed to evaluate the radial preloading effects on the bored piles bearing capacity under upward loading. Verification of the numerical model was conducted by comparing the calculated allowable load capacity based on a series of physical models in the small scale. Interpretations of the finite elements models were focused on the load-displacement behaviour, the effect of the increase in the pile diameter on the pile load capacity, deformation of the surrounding soil due to radial preloading and comparison of different constitutive models. The results revealed that the bearing capacity is increased due to impose of radial preloading for bored piles, meaningfully. In addition, the effect of the radial preloading is increased on the bearing capacity with increase in the pile diameter. In another aspect, the simulation of the pile behaviours based on the different constitutive models demonstrated that soft soil model can properly simulate pile behaviour due to radial preloading in comparison with Mohr-Coulomb model.

Fizikalno-kemijska karakterizacija kaolinske gline s dodatkom cementa

U ovom radu je predstavljena fizikalno-kemijska karakterizacija smeđe kaolinske gline s dodatkom cementa. Istražuje se utjecaj cementa na čvrstoću i stišljivost glinenih uzoraka uz variranje vremena njege i količine cementa. Na glinenim uzorcima s dodatkom 5 i 10 posto cementa obavljena su laboratorijska ispitivanja zbijenosti, jednoosne tlačne čvrstoće i jednodimenzionalne konsolidacije pomoću edometra. Rezultati ispitivanja čvrstoće i stišljivosti, provedenih tijekom dužega razdoblja, upućuju na porast jednoosne tlačne čvrstoće te na smanjenje indeksa stišljivosti.The physicochemical characterization of the cement-treated brown kaolin clay is presented in this paper. The effect of cement on the strength and compressibility of clay samples, at different curing times and cement contents, is investigated. Laboratory tests including compaction, unconfined compressive strength, and one-dimensional consolidation oedometer tests, were carried out on clay samples mixed with 5 % and 10 % of cement. Long-term strength and compressibility test results point to an increase in the unconfined compressive strength and decrease in the compression index.

An Experimental Study on Pile Spacing Effects under Lateral Loading in Sand

Grouped and single pile behavior differs owing to the impacts of the pile-to-pile interaction. Ultimate lateral resistance and lateral subgrade modulus within a pile group are known as the key parameters in the soil-pile interaction phenomenon. In this study, a series of experimental investigation was carried out on single and group pile subjected to monotonic lateral loadings. Experimental investigations were conducted on twelve model pile groups of configurations 1 × 2, 1 × 3, 2 × 2, 3 × 3, and 3 × 2 for embedded length-to-diameter ratio l/d = 32 into loose and dense sand, spacing from 3 to 6 pile diameter, in parallel and series arrangement. The tests were performed in dry sand from Johor Bahru, Malaysia. To reconstruct the sand samples, the new designed apparatus, Mobile Pluviator, was adopted. The ultimate lateral load is increased 53% in increasing of s/d from 3 to 6 owing to effects of sand relative density. An increasing of the number of piles in-group decreases the group efficiency owing to the increasing of overlapped stress zones and active wedges. A ratio of s/d more than 6d is large enough to eliminate the pile-to-pile interaction and the group effects. It may be more in the loose sand.

Effect of Humic Acid on Geochemistry Properties of Kaolin

Organic soil is always known as problematic soil because of its engineering properties are inferior from other soft soils and/or because its behaviour may deviate from traditional rules of soil behaviour which makes it difficult to predict and design. Considerable research has been carried out over the years on organic soils, particularly peat soil which consists of various components of organic matter but the effect of particular organic matter is less reported. Hence, this study is carried out to determine the effect of humic acid (a kind of humified organic matter) on kaolin (which is widely studied). This paper addresses the influence of humic acid (30% and 50% of dry mass) on kaolins geochemistry properties namely Atterberg limits, compaction, specific gravity and Loss on Ignition (LOI). The findings of the study showed that the contents of humic acid had altered the behaviour of kaolin. The loss on ignition increased linearly with the increment of humic acid. However, the specific gravity, maximum dry density and Atterberg limits decreased with addition of humic acid. Atterberg limits decreased as the humic acid increased is believed to be due to the nature of humic acid which precipitated under acidic environment.

Removal of Suspended Colloids through the Control of Their Zeta Potential

The effect of CaO, Na2SiO3, Al(OH)3, Al2(SO4)3, and CaCl2 on the surface charge and the diffuse double layer (DDL) thickness of a natural tropical peat were investigated in this study. Consequently, the flocculation and coagulation behavior of peat colloids were studied. As result, the thickness of DDL were changed significantly due to the addition of each electrolytes. The compression of the DDL thickness causes a weaker electrostatic repulsion and therefore a higher settlement rate. The surface charge of pure peat was almost zero at pH 3.2. The pH at the isoelectric point was increased by increasing the electrolyte concentration. The resulted flocculation and coagulation behavior of suspended peat in cationic reagents was in contrary with the surface electrical charge characteristics where the Na2SiO3 and the Al2(SO4)3 electrolytes showed the lowest and highest settlement rate, respectively.

Stabilization of Artificial Organic Soil at Room Temperature using Blended Lime Zeolite

Organic content in soil is believed to inhibit formation of reaction products in lime stabilization which resulted in low gain of strength when dealing with organic soils. Zeolite, a kind of pozzolan with high CEC capacity is proposed to be use in this study in order to improve lime stabilization of organic soil. The effectiveness of blended lime zeolite in stabilization of organic soils was investigated by using two types of artificial organic soils with predetermined organic contents. Artificial organic soils were formed by mixing inorganic soil (commercial kaolin) with organic matter (commercial humic acid) at specific ratio. Initial consumption of lime for organic soils was determined in order to determine the minimum percentage of stabilizer required for each soil. Potential influencing factors that might affect the strength such as organic contents, contents of stabilizer, and curing periods were studied. The findings of the study showed that high organic contents and low lime contents resulted in lower gain of strength. However, it is found that slight replacement of lime with zeolite works well with low organic soil at long curing period which resulted in highest strength among all the mixes. Overall, longer curing periods will increase the strength of the soil in the order of 56 days > 28 days > 7 days. Nevertheless, the percentage of strength increment over curing periods is linear with the lime contents, which proved that lime is required for pozzolanic reaction.